Le pH d'une solution 0,15 M d'éthylamine C2 H5 NH2 est trouvé égal à 12,0 . >Quelle est la valeu

step 1 In this question, P -K of ethyl ammonium ion is given 10 .70 and we have to find out the pH of 0

Le pH d'une solution 0,15 M d'éthylamine C2 H5 NH2 est...

Le $\mathrm{pH}$ d'une solution $0,15 \mathrm{M}$ d'éthylamine $\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_2$ est trouvé égal à 12,0 . >Quelle est la valeur de la constante d'acidité du couple $\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_3{ }^{+}$/ $\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_2$ ? > Quelle est, dans cette solution, la valeur du rapport $\left[\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_3{ }^{+}\right]$ $\left[\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_2\right]$ ?

Le $\mathrm{pH}$ d'une solution $0,15 \mathrm{M}$ d'éthylamine $\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_2$ est trouvé égal à 12,0 .
>Quelle est la valeur de la constante d'acidité du couple $\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_3{ }^{+}$/ $\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_2$ ?
> Quelle est, dans cette solution, la valeur du rapport $\left[\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_3{ }^{+}\right]$ $\left[\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_2\right]$ ?

Key Concepts

Logarithmic pH Scale

The pH scale is a logarithmic representation of the hydrogen ion concentration in a solution. Because the scale is logarithmic, each unit change in pH corresponds to a tenfold change in hydrogen ion concentration. This concept is vital in the study of acid–base chemistry, as it allows chemists to easily compare the acidity or basicity of different solutions.

Henderson–Hasselbalch Equation

The Henderson–Hasselbalch equation relates the pH of a solution to the pKa of the acid and the ratio of the concentrations of the conjugate base and the acid. This equation is particularly useful for buffer solutions and for problems involving the protonation of a weak base, as it provides a straightforward way to evaluate the relative amounts of a conjugate pair and to understand how changes in concentration or pH impact the system.

Acid?Base Equilibrium

Acid?base equilibrium refers to the reversible reactions in which acids donate protons and bases accept protons in aqueous solution. This equilibrium is characterized by the establishment of a balance between the concentrations of the acid, its conjugate base, the base, and its conjugate acid. Analyzing these equilibria provides insight into the strengths of acids and bases and how they interact with water.

Conjugate Acid–Base Pair

A conjugate acid–base pair consists of two species that differ by one proton. When an acid donates a proton, it forms its conjugate base; conversely, when a base accepts a proton, it forms its conjugate acid. This pair is central to understanding how substances behave under acid–base conditions and how their equilibrium constants are interrelated.

Equilibrium Constant Relationships (Ka, Kb, and Kw)

The acid dissociation constant (Ka) and the base dissociation constant (Kb) quantify the strength of an acid and its corresponding base in water, respectively. These constants are interconnected through the ion product constant of water (Kw) by the relationship Ka × Kb = Kw. This relationship allows the determination of one constant when the other is known and is essential for analyzing conjugate acid–base pairs in aqueous solutions.

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